Electronic component and method for manufacturing the same

ABSTRACT

In an electronic component, an outer electrode includes a sintered layer containing a sintered metal, an insulation layer containing an electric insulation material, and a Sn-containing layer containing Sn. The sintered layer extends from each of end surfaces of an element assembly onto at least one main surface thereof so as to cover each of the end surfaces of the element assembly. The insulation layer is directly provided on the sintered layer at each of the end surfaces of the element assembly so as to extend in a direction perpendicular or substantially perpendicular to a side surface of the element assembly, and defines a portion of a surface of the outer electrode. The Sn-containing layer covers the sintered layer except for a portion of the sintered layer that is covered by the insulation layer, and constitutes another portion of the surface of the outer electrode.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to electronic components and methods for manufacturing electronic components, and more specifically relates to electronic components mounted by soldering and methods for manufacturing the electronic components.

2. Description of the Related Art

Japanese Unexamined Patent Application Publication No. 2003-22929 describes a multilayer ceramic capacitor in which an occurrence of a short circuit of inner electrodes due to a crack generated by thermal contraction of a solder fillet is suppressed.

In the multilayer ceramic capacitor described in Japanese Unexamined Patent Application Publication No. 2003-22929, in the case where a crack is generated in an element assembly in the vicinity of one outer electrode thereof by tension of a solder fillet, inner electrodes connected to the other outer electrode are prevented from being exposed in a gap of the crack. This suppresses occurrence of a short circuit of the inner electrodes when moisture enters into the crack.

In the case where a crack is generated in the element assembly by tensile stress due to thermal contraction of the solder fillet and causes the inner electrodes to be cut, electrostatic capacity of the multilayer ceramic capacitor drops. As described above, in the case where a crack is generated in an electronic component by tensile stress due to thermal contraction of a solder fillet, electric characteristics of the electronic component are deteriorated as a result.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide electronic components and methods for manufacturing the electronic components in which an occurrence of a crack in an element assembly by tensile stress due to thermal contraction of a solder fillet is significantly reduced or prevented.

An electronic component according to a preferred embodiment of the present invention includes an element assembly in which inner electrodes are embedded and that includes a pair of main surfaces, a pair of side surfaces respectively connecting the main surfaces, and a pair of end surfaces respectively perpendicular or substantially perpendicular to the pair of main surfaces and the pair of side surfaces, and an outer electrode provided on a surface of the element assembly and electrically connected with the inner electrodes. In the electronic component, the outer electrode includes a sintered layer containing a sintered metal, an insulation layer made of an electric insulation material, and a Sn-containing layer that contains Sn. The sintered layer is extends from each of the end surfaces onto at least one of the main surfaces so as to cover each of the end surfaces. The insulation layer is directly provided on the sintered layer at each of the end surfaces so as to extend in a direction perpendicular or substantially perpendicular to the side surfaces and constitutes a portion of a surface of the outer electrode. The Sn-containing layer is arranged so as to cover the sintered layer except for a portion of the sintered layer that is covered by the insulation layer and constitutes another portion of the surface of the outer electrode.

The Sn-containing layer preferably extends from each of the end surfaces to one of the main surfaces.

Preferably, none of the inner electrodes are located in a virtual plane that links the position of an edge on one of the main surfaces in the insulation layer at the end surface with the position of a tip of the outer electrode on one of the main surfaces in the shortest distance.

The insulation layer preferably is directly provided on the sintered layer at each of the end surfaces so that at least a portion of the insulation layer is located between one of the main surfaces and the position of an edge portion of the inner electrode closest to one of the main surfaces in a direction perpendicular or substantially perpendicular to the main surface.

The sintered layer preferably is arranged so as to further extend from each of the end surfaces onto each of the side surfaces. The insulation layer preferably is further provided directly on the sintered layer at each of the side surfaces so as to extend in a direction perpendicular or substantially perpendicular to the end surface.

The outer electrode preferably further includes a reinforcement layer containing Ni or Cu. The reinforcement layer is provided between the sintered layer and the Sn-containing layer.

The outer electrode preferably further includes a base layer which is made of a material different from that of the reinforcement layer and contains Cu or Ni. The base layer is provided between the sintered layer and the reinforcement layer.

A method for manufacturing an electronic component according to another preferred embodiment of the present invention includes the steps of preparing an element assembly in which inner electrodes are embedded and that includes a pair of main surfaces, a pair of side surfaces respectively connecting the main surfaces, and a pair of end surfaces respectively perpendicular or substantially perpendicular to the pair of main surfaces and the pair of side surfaces, and providing an outer electrode on a surface of the element assembly so that the outer electrode is electrically connected with the inner electrodes. The process of providing the outer electrode includes a step of providing a sintered layer containing a sintered metal, a step of providing an insulation layer formed of an electric insulation material, and a step of providing a Sn-containing layer that contains Sn. In the step of providing the sintered layer, the sintered layer is formed to extend from each of the end surfaces onto at least one of the main surfaces so as to cover each of the end surfaces. In the step of providing the insulation layer, the insulation layer is directly provided on the sintered layer at each of the end surfaces to extend in a direction perpendicular or substantially perpendicular to the side surfaces so as to constitute a portion of a surface of the outer electrode. In the step of providing the Sn-containing layer, the Sn-containing layer is provided to cover the sintered layer except for a portion of the sintered layer that is covered by the insulation layer so as to constitute another portion of the surface of the outer electrode.

In the step of providing the Sn-containing layer, the Sn-containing layer preferably is formed to extend from each of the end surfaces to one of the main surfaces.

In the step of providing the outer electrode, the outer electrode preferably is provided so that none of the inner electrodes are located in a virtual plane which links the position of an edge of the insulation layer at the end surface on one of the main surfaces with the position of a tip of the outer electrode on one of the main surfaces in the shortest distance.

In the step of providing the insulation layer, the insulation layer preferably is directly provided on the sintered layer at each of the end surfaces so that at least a portion of the insulation layer is located between one of the main surfaces and the position of an edge portion of the inner electrode closest to one of the main surfaces in a direction perpendicular or substantially perpendicular to the main surface.

In the step of providing the sintered layer, the sintered layer preferably is provided so as to further extend from each of the end surfaces onto each of the side surfaces. In the step of providing the insulation layer, the insulation layer preferably is further provided directly on the sintered layer at each of the side surfaces so as to extend in a direction perpendicular or substantially perpendicular to the end surface.

The step of providing the outer electrode preferably further includes a process of providing a reinforcement layer containing Ni or Cu. In the step of providing the reinforcement layer, the reinforcement layer preferably is provided between the sintered layer and the Sn-containing layer.

The step of providing the outer electrode preferably further includes a process of providing a base layer which is formed of a material different from that of the reinforcement layer and contains Cu or Ni. In the step of providing the base layer, the base layer preferably is provided between the sintered layer and the reinforcement layer.

In the step of providing the sintered layer, a dielectric layer included in the element assembly and the sintered layer preferably are baked at the same time.

According to various preferred embodiments of the present invention, an occurrence of a crack in an element assembly by tensile stress due to thermal contraction of a solder fillet is significantly reduced or prevented.

The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an external appearance of an electronic component according to a first preferred embodiment of the present invention.

FIG. 2 is a cross-sectional view of the electronic component taken along a II-II arrow line in FIG. 1.

FIG. 3 is a cross-sectional view of the electronic component taken along a III-III arrow line in FIG. 2.

FIG. 4 is a cross-sectional view of the electronic component taken along a IV-IV arrow line in FIG. 2.

FIG. 5 is a cross-sectional view of the electronic component taken along a V-V arrow line in FIG. 2.

FIG. 6 is a flowchart illustrating a method for manufacturing an electronic component according to the first preferred embodiment of the present invention.

FIG. 7 is a perspective view illustrating a state in which the electronic component according to the first preferred embodiment of the present invention is mounted on a substrate by soldering.

FIG. 8 is a cross-sectional view illustrating a configuration of an electronic component according to a second preferred embodiment of the present invention.

FIG. 9 is a flowchart illustrating a method for manufacturing the electronic component according to the second preferred embodiment of the present invention.

FIG. 10 is a cross-sectional view illustrating a configuration of an electronic component according to a third preferred embodiment of the present invention.

FIG. 11 is a flowchart illustrating a method for manufacturing the electronic component according to the third preferred embodiment of the present invention.

FIG. 12 is a perspective view illustrating an external appearance of an electronic component according to a fourth preferred embodiment of the present invention.

FIG. 13 is a cross-sectional view of the electronic component taken along a XIII-XIII arrow line in FIG. 12.

FIG. 14 is a perspective view illustrating an external appearance of an electronic component according to a fifth preferred embodiment of the present invention.

FIG. 15 is a cross-sectional view of the electronic component taken along a XV-XV arrow line in FIG. 14.

FIG. 16 is a cross-sectional view of the electronic component taken along a XVI-XVI arrow line in FIG. 14.

FIG. 17 is a cross-sectional view of the electronic component taken along a XVII-XVII arrow line in FIG. 15 and of the electronic component taken along the XVII-XVII arrow line in FIG. 16 as well.

FIG. 18 is a cross-sectional view of the electronic component taken along a XVIII-XVIII arrow line in FIG. 15 and of the electronic component taken along the XVIII-XVIII arrow line in FIG. 16 as well.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an electronic component according to preferred embodiments of the present invention will be described with reference to the drawings. In the following description of the preferred embodiments, identical or equivalent members in the drawings are given identical reference numerals and description thereof is not repeated. Further, in the following description, although a multilayer ceramic capacitor will be explained as an electronic component, the electronic component is not intended to be limited to the multilayer ceramic capacitor, and may be a piezoelectric component, a thermistor, an inductor, or the like.

First Preferred Embodiment

FIG. 1 is a perspective view illustrating an external appearance of an electronic component according to a first preferred embodiment of the present invention. FIG. 2 is a cross-sectional view of the electronic component taken along a II-II arrow line in FIG. 1. FIG. 3 is a cross-sectional view of the electronic component taken along a III-III arrow line in FIG. 2. FIG. 4 is a cross-sectional view of the electronic component taken along a IV-IV arrow line in FIG. 2. FIG. 5 is a cross-sectional view of the electronic component taken along a V-V arrow line in FIG. 2. In FIG. 1, a lengthwise direction of an element assembly, which will be explained later in detail, is indicated by “L”, a width direction of the element assembly is indicated by “W”, and a thickness direction of the element assembly is indicated by “T”.

As shown in FIGS. 1 through 5, an electronic component 100 according to the first preferred embodiment of the present invention includes a parallelepiped-shaped element assembly 110 in which inner electrodes 130 are embedded, and an outer electrode 120 provided on a surface of the element assembly 110 and electrically connected with the inner electrodes 130.

In the element assembly 110, dielectric layers 140 and the inner electrodes 130 having a plate shape are alternately stacked. A stacking direction of the dielectric layers 140 and the inner electrodes 130 is perpendicular or substantially perpendicular to both the lengthwise direction L of the element assembly 110 and the width direction W of the element assembly 110. In other words, the stacking direction of the dielectric layers 140 and the inner electrodes 130 is parallel to the thickness direction T of the element assembly 110.

The element assembly 110 includes a pair of main surfaces perpendicular or substantially perpendicular to the thickness direction T, a pair of end surfaces perpendicular or substantially perpendicular to the lengthwise direction L, and a pair of side surfaces perpendicular or substantially perpendicular to the width direction W. The pair of main surfaces includes one main surface 10 and the other main surface 11. The one main surface 10 is a surface positioned on a mounting surface of the electronic component 100 when mounted. In other words, when the electronic component 100 is mounted on a substrate, the one main surface 10 is a surface that opposes the substrate.

As described above, the element assembly 110 includes the pair of main surfaces perpendicular or substantially perpendicular to the stacking direction of the dielectric layers 140 and the inner electrodes 130, the pair of side surfaces respectively connecting the main surfaces, and the pair of end surfaces respectively perpendicular or substantially perpendicular to the pair of main surfaces and the pair of side surfaces.

Although the element assembly 110 preferably has a parallelepiped shape with its corners being rounded, the corners of the assembly may not be rounded. Furthermore, concave and/or convex portions may be formed in any one of the surfaces included in the pair of main surfaces, the pair of end surfaces, or the pair of side surfaces.

In the inner electrodes 130 adjacent to each other and opposing each other, one inner electrode 130 is electrically connected with the outer electrode 120 at one end surface of the element assembly 110, while the other inner electrode 130 is electrically connected with the outer electrode 120 at the other end surface of the element assembly 110.

Details of the constituent elements will be described hereinafter.

As a material that configures the dielectric layer 140, dielectric ceramics whose major component is BaTiO₃, CaTiO₃, SrTiO₃, CaZrO₃, or the like can be used. Further, a material in which a Mn compound, a Co compound, a Si compound, a rare earth compound, or the like is added as an accessory component to the above major component, may be used.

The inner electrodes 130 preferably have a rectangular or approximately rectangular shape when viewed from above. The inner electrodes 130 adjacent to each other in the stacking direction oppose each other sandwiching the dielectric layer 140 therebetween. The one inner electrodes 130 and the other inner electrodes 130 mentioned above are alternately disposed at equal or substantially equal intervals along the thickness direction T of the element assembly 110.

The one inner electrode 130 extends from one end surface of the element assembly 110 toward the other end surface thereof. As shown in FIG. 3, the one inner electrode 130 is connected with a sintered layer 121 of the outer electrode 120, which will be explained later, at the one end surface of the element assembly 110.

The other inner electrode 130 extends from the other end surface of the element assembly 110 toward the one end surface thereof. As shown in FIG. 4, the other inner electrode 130 is connected with the sintered layer 121 of the outer electrode 120, which will be explained later, at the other end surface of the element assembly 110.

As a material that configures the inner electrode 130, a metal such as Ni, Cu, Ag, Pd, Au, Pt, Sn or the like, or an alloy including at least one of the above metals, for example, an alloy including Ag and Pd, can be used. In the present preferred embodiment, the inner electrode 130 is made of Ni.

As shown in FIG. 2, the outer electrode 120 includes the sintered layer 121 containing a sintered metal, an insulation layer 122 made of an electric insulation material, and a Sn-containing layer 123 that contains Sn.

The sintered layer 121 extends from each of the end surfaces onto at least the one main surface 10 so as to cover the end surfaces of the element assembly 110. In the present preferred embodiment, the sintered layer 121 extends from the one end surface onto both the main surfaces and the side surfaces while covering the whole one end surface of the element assembly 110. Further, the sintered layer 121 extends from the other end surface onto both the main surfaces and the side surfaces while covering the whole the other end surface of the element assembly 110. The sintered layer 121 extending from the one end surface of the element assembly 110 onto both the main surfaces and the side surfaces thereof and the sintered layer 121 extending from the other end surface of the element assembly 110 onto both the main surfaces and the side surfaces thereof, are separated from each other and not electrically connected.

As a material of the sintered layer 121, a metal such as Ni, Cu, Ag, Pd or the like, or a conductive paste whose major component is an alloy containing at least one of the above metals, can be used. In the present preferred embodiment, a conductive paste whose major component is Cu is applied on the surface of the element assembly 110 and heated at a temperature of approximately 700° C., for example, so that the sintered layer 121 is baked and fixed to the element assembly 110.

The sintered layer 121 contains a glass component. In the sintered layer 121, the glass content percentage is higher in a surface layer portion than in an inside portion. By making the glass content percentage higher in the surface layer portion of the sintered layer 121, adhesiveness between the insulation layer 122 and the sintered layer 121 to be explained later is increased so as to significantly reduce or prevent separation of the insulation layer 122 at a time of plating or mounting to be explained later.

The insulation layer 122 is directly provided on the sintered layer 121 at each of the end surfaces so as to extend in the width direction W, which is a direction perpendicular or substantially perpendicular to the side surface of the element assembly 110, and constitutes a portion of the surface of the outer electrode 120.

In the present preferred embodiment, the insulation layer 122 extends across the entirety in the width direction W of the element assembly 110 at each end surface of the element assembly 110. As shown in FIG. 2, none of the inner electrodes 130 are located in a virtual plane P₁ that links the position of an edge of the insulation layer 122 at the end surface of the element assembly 110 on the one main surface 10 with the position of a tip of the outer electrode 120 on the one main surface 10 of the element assembly 110 in the shortest distance.

In the present preferred embodiment, as shown in FIG. 2, although none of the inner electrodes 130 intersect with virtual lines defining the virtual plane P₁ in a cross section of the electronic component 100 on an arbitrary surface in parallel to the side surface of the element assembly 110, the inner electrodes 130 intersecting with the virtual lines may be included therein. However, it is preferable that none of the inner electrodes 130 intersect with the virtual lines.

The insulation layer 122 is directly provided on the sintered layer 121 at each end surface of the element assembly 110 such that at least a portion of the insulation layer 122 is located between the one main surface 10 of the element assembly 110 and the position of an edge portion of the inner electrode 130 closest to the one main surface 10 of the element assembly 110 in the thickness direction T, which is a direction perpendicular or substantially perpendicular to the main surfaces of the element assembly 110.

To be more specific, in the case where a dimension of distance between the one main surface 10 of the element assembly 110 and the edge portion on the one main surface 10 of the inner electrode 131 closest to the one main surface 10 is taken as L₁, a dimension of distance L₂ along the thickness direction T of the element assembly 110 between the one main surface 10 of the element assembly 110 and the position of an end portion on the one main surface 10 of the insulation layer 122 satisfies a relation of L₂<L₁ at each end surface of the element assembly 110.

In the present preferred embodiment, L₂>0; that is, of the sintered layer 121 provided at each of the end surfaces of the element assembly 110, only a portion of the sintered layer 121 on the one main surface 10 is not covered by the insulation layer 122. In the case where a dimension of thickness of the element assembly 110 is taken as L_(T), it is preferable for a relation of L₂>L_(T)/10 to be satisfied for the reason to be explained later. Accordingly, in the electronic component 100, it is preferable for both the relation of L₂<L₁ and the relation of L₂>L_(T)/10 to be satisfied. The electronic component 100 satisfies a relation of L_(T)/10<L₂<L₁ in the present preferred embodiment.

The insulation layer 122 extends in the lengthwise direction L, which is a direction perpendicular or substantially perpendicular to the end surface of the element assembly 110, at each of the side surfaces of the element assembly 110. In the present preferred embodiment, the insulation layer 122 extends across the entirety of each side surface of the element assembly 110 along the lengthwise direction L of the element assembly 110. In other words, a portion of the insulation layer 122 is directly provided on the sintered layer 121 at each side surface of the element assembly 110. Another portion of the insulation layer 122 is directly provided on each side surface of the element assembly 110.

The insulation layer 122 provided at each end surface of the element assembly 110 and the insulation layer 122 provided at each side surface of the element assembly 110 are connected with each other so as to form a ring-shaped configuration. At each side surface of the element assembly 110, L₂ is the dimension of distance along the thickness direction T of the element assembly 110 between the one main surface 10 of the element assembly 110 and the position of the end portion on the one main surface 10 of the insulation layer 122.

Further, the insulation layer 122 covers the entirety of the other main surface 11 of the element assembly 110. In other words, a portion of the insulation layer 122 is directly provided on the sintered layer 121 at the other main surface 11 of the element assembly 110. Another portion of the insulation layer 122 is directly provided on the other main surface 11 of the element assembly 110. The insulation layer 122 covering the other main surface 11 of the element assembly 110 is connected with the insulation layer 122 provided at each end surface of the element assembly 110 and the insulation layer 122 provided at each side surface of the element assembly 110, respectively.

As described above, portions of the insulation layer 122 are directly provided on the other main surface 11 of the element assembly 110 and the side surfaces of the element assembly 110. The insulation layer 122 has a higher adhesiveness with the element assembly 110 than with the sintered layer 121. Therefore, providing a portion of the insulation layer 122 directly on the element assembly 110 makes it possible to significantly reduce or prevent the separation of the insulation layer 122 at the time of plating or mounting to be explained later.

As a material that configures the insulation layer 122, insulating resin such as a thermosetting curing insulating resin, an ultraviolet curing insulating resin, or the like serving as solder resist can be used.

The Sn-containing layer 123 is provided on the sintered layer 121 so as to cover the sintered layer 121 except for a portion of the sintered layer 121 that is covered by the insulation layer 122 and constitutes another portion of the surface of the outer electrode 120.

In the present preferred embodiment, the Sn-containing layer 123 extends from each end surface of the element assembly 110 to the one main surface 10 thereof. As described above, of the sintered layer 121 provided at each end surface of the element assembly 110, only a portion of the sintered layer 121 on the one main surface 10 is not covered by the insulation layer 122. Accordingly, at each end surface of the element assembly 110, the Sn-containing layer 123 covers the portion of the sintered layer 121 that is positioned on the one main surface 10 and is not covered by the insulation layer 122.

In addition, the Sn-containing layer 123 covers the sintered layer 121 that is not covered by the insulation layer 122 at the one main surface 10 of the element assembly 110. Furthermore, at each side surface of the element assembly 110, the Sn-containing layer 123 covers a portion of the sintered layer 121 that is positioned on the one main surface 10 and is not covered by the insulation layer 122.

As described above, the sintered layer 121 extends from the one end surface of the element assembly 110 onto both the main surfaces and the side surfaces thereof. Further, the sintered layer 121 extends from the other end surface of the element assembly 110 onto both the main surfaces and the side surfaces thereof.

As such, the Sn-containing layer 123 extends from the one end surface of the element assembly 110 to the one main surface 10 and to the side surfaces thereof. Further, the Sn-containing layer 123 extends from the other end surface of the element assembly 110 to the one main surface 10 and to the side surfaces thereof.

The Sn-containing layer 123 extending from the one end surface of the element assembly 110 to the one main surface 10 as well as to the side surfaces of the element assembly 110 and the Sn-containing layer 123 extending from the other end surface of the element assembly 110 to the one main surface 10 as well as to the side surfaces of the element assembly 110, are separated from each other and not electrically connected.

As a material that configures the Sn-containing layer 123, Sn or a Sn alloy, which has a preferable wettability with respect to solder, can be used.

Hereinafter, a non-limiting example of a method for manufacturing an electronic component according to the present preferred embodiment will be described. FIG. 6 is a flowchart illustrating a non-limiting example of a method for manufacturing an electronic component according to the present preferred embodiment. As shown in FIG. 6, the method includes a process of preparing the element assembly 110 (S100), and a process of providing an outer electrode 120 on the surface of the element assembly 110 for the outer electrode 120 to be electrically connected with the inner electrodes 130 (S110).

The element assembly 110 preferably is manufactured as follows.

First, a ceramic paste containing ceramic powder is applied by a die coater method, a gravure coater method, a micro-gravure coater method, or the like in a sheet-shaped state, then the applied paste is dried so as to form a ceramic green sheet.

In some of a plurality of manufactured ceramic green sheets, a conductive paste for forming the inner electrodes is applied on the ceramic green sheets by screen printing, ink jet printing, gravure printing, or the like so that the applied paste forms a predetermined pattern. In this manner, the ceramic green sheets in which the conductive pattern configuring the inner electrodes is formed and the ceramic green sheets in which the conductive patter is not formed are prepared. Note that a known binder and a known solvent may be contained in the ceramic paste and the conductive paste for forming the inner electrodes.

A predetermined number of the ceramic green sheets without the conductive pattern being formed therein are stacked on each other, a plurality of ceramic green sheets with the conductive pattern being formed therein are sequentially stacked on the ceramic green sheets, and then a predetermined number of the ceramic green sheets without the conductive pattern being formed therein are stacked on the sheets with the conductive pattern being formed so as to manufacture a mother block. The mother block may be pressed in the stacking direction using a hydrostatic press method or the like as needed.

By dividing the mother block through cutting into a predetermined shape, a plurality of soft element assemblies each having a parallelepiped shape are manufactured. The parallelepiped soft element assemblies undergo barrel-polishing so that the corners of each of the soft element assemblies are rounded. However, the barrel-polishing is not necessarily needed to be carried out.

The soft element assembly is baked and hardened so as to manufacture the element assembly 110. A temperature at which the baking is carried out is appropriately set in accordance with the respective types of ceramic materials and conductive materials, that is, for example, the temperature is set within a range of no less than approximately 900° C. and no more than approximately 1,300° C.

The process of providing the outer electrode 120 (S110) includes a process of providing the sintered layer 121 containing a sintered metal (S111), a process of providing the insulation layer 122 formed of an electric insulation material (S112), and a process of providing the Sn-containing layer 123 that contains Sn (S113).

In the process of providing the sintered layer 121 (S111), the sintered layer 121 extends from each end surface of the element assembly 110 onto at least the one main surface of the element assembly 110 so as to cover each end surface of the element assembly 110. In the present preferred embodiment, the conductive paste to become the sintered layer 121 is applied to both end portions of the element assembly 110 by a dip method. In this manner, in the process of providing the sintered layer 121 (S111), the sintered layer 121 extends from each end surface of element assembly 110 onto the main surfaces of the element assembly 110 as well as onto the side surfaces thereof.

As described above, in the present preferred embodiment, the conductive paste whose major component is Cu is applied on the surface of the element assembly 110 and heated at a temperature of, for example, approximately 700° C. so that the sintered layer 121 is baked and fixed on the element assembly 110.

A plurality of sintered layers 121 being layered on each other may be provided by repeating the application and drying of the conductive paste. In this case, in order to raise the glass content percentage in the sintered layer 121 positioned in the surface layer, it is preferable to set the glass content percentage of the conductive paste which is applied later to be higher than the glass content percentage of the conductive paste which is applied earlier. This increases the adhesiveness between the sintered layer 121 and the insulation layer 122 that is formed later, thus making it possible to significantly reduce or prevent the separation of the insulation layer 122 at the time of plating or mounting to be explained later.

In the process of providing the sintered layer (S111), the dielectric layer 140 and the sintered layer 121 may be baked at the same time. In other words, by carrying out baking after the conductive paste is applied on the soft element assembly, the element assembly 110 and the sintered layer 121 may be formed at the same time.

In the process of providing the insulation layer 122 (S112), the insulation layer 122 is directly provided on the sintered layer 121 at each end surface of the element assembly 110 so as to extend in the width direction W, which is a direction perpendicular or substantially perpendicular to the side surface of the element assembly 110, and to constitute a portion of the surface of the outer electrode 120.

In the present preferred embodiment, the insulation layer 122 preferably is provided by spray-coating of insulating resin such as a thermosetting curing insulating resin, an ultraviolet curing insulating resin, or the like serving as solder resist.

To be more specific, the plurality of element assemblies 110 each provided with the sintered layer 121 are mounted on a plate including a plurality of recesses. Each of the element assemblies 110 provided with the sintered layer 121 is disposed so that the one main surface 10 is accommodated in the recess. The shape of the recess is slightly a size larger than the shape of the main surface 10 of the element assembly 110 provided with the sintered layer 121 when viewed from above. The dimension in depth of the recess is so set as to be equal or approximately equal to the above-mentioned dimension L₂. As described earlier, the dimension L₂ preferably satisfies the relation of L_(T)/10<L₂<L₁.

With spray-coating performed in a state in which the element assembly 110 is accommodated in the recess, the insulating resin can be applied to a portion of the element assembly 110 that is not accommodated in the recess. As a result, as shown in FIG. 1, the insulation layer 122 is provided at the end surfaces, the side surfaces, and the other main surface 11 of the element assembly 110.

As described above, in the present preferred embodiment, in the process of providing the insulation layer 122 (S112), the insulation layer 122 is further provided on the sintered layer 121 at the side surfaces of the element assembly 110 so as to extend in the lengthwise direction L as a direction perpendicular or substantially perpendicular to the end surface of the element assembly 110.

By setting the dimension in depth of the recess to be the same or approximately the same as the dimension L₂, in the process of providing the insulation layer 122 (S112), the insulation layer 122 is directly provided on the sintered layer 121 at each end surface of the element assembly 110 so that at least a portion of the insulation layer 122 is located between the one main surface 10 of the element assembly 110 and the position of the edge portion of the inner electrode 130 closest to the one main surface 10 of the element assembly 110 in the thickness direction T as a direction perpendicular or substantially perpendicular to the main surface of the element assembly 110.

In the case where a thermosetting curing insulating resin is used as the insulating resin, the insulating resin is cured by heating the element assembly 110 on which the spray-coating has been performed. In the case where an ultraviolet curing insulating resin is used as the insulating resin, the insulating resin is cured by irradiating the element assembly 110, on which the spray-coating has been performed, with ultraviolet light.

It is preferable for thickness of the insulation layer 122 formed of the cured insulating resin to be no less than approximately 10 μm and no more than approximately 50 μm. It is more preferable for the thickness of the insulation layer 122 to be no less than approximately 15 μm and no more than approximately 30 μm.

In the case where the thickness of the insulation layer 122 is smaller than approximately 10 μm, because tensile strength of the insulation layer 122 is insufficient, the insulation layer 122 can be separated or fractured at a time of plating to be explained later when agitation for plating is made in a plating bath. In the case where the thickness of the insulation layer 122 is larger than approximately 50 μm, because the insulation layer 122 is in a state of projecting to an outer side portion from the shape of the electronic component, an external force is likely to act on the insulation layer 122 at the time of plating to be explained later when the agitation for plating is made in the plating bath, which causes the insulation layer 122 to be easily separated.

The method for forming the insulation layer 122 is not intended to be limited to spray-coating; that is, for example, a dip method, a screen printing method, a photolithography method, or the like may be used instead. As another method for forming the insulation layer 122, the following may be employed, for example. That is, in a state in which the plurality of element assemblies 110 provided with the sintered layer 121 are held on a plate with a space therebetween, a softened insulating resin is poured over the plate, thereby applying the insulating resin on the surface of each of the element assemblies 110 provided with the sintered layer 121.

In the process of providing the Sn-containing layer 123 (S113), the Sn-containing layer 123 is provided so as to cover the sintered layer 121 except for a portion of the sintered layer 121 that is covered by the insulation layer 122 to constitute another portion of the surface of the outer electrode 120.

In the present preferred embodiment, the Sn-containing layer 123 is preferably formed by electroplating, for example. More specifically, the Sn-containing layer 123 is preferably formed by barrel-plating, for example. A barrel accommodating the plurality of element assemblies 110 provided with the sintered layer 121 and the insulation layer 122 is immersed in a plating liquid within a plating bath, and is electrified while the barrel being rotated in the plating liquid, such that the Sn-containing layer 123 is formed on the sintered layer 121 except for a portion of the sintered layer 121 that is covered by the insulation layer 122.

As described above, of the sintered layer 121 provided at each end surface of the element assembly 110, only a portion of the sintered layer that is on the one main surface 10 is not covered by the insulation layer 122. Accordingly, the Sn-containing layer 123 covers the portion of the sintered layer 121 that is positioned on the one main surface 10 and is not covered by the insulation layer 122 at each end surface of the element assembly 110. Further, the Sn-containing layer 123 is configured to cover the sintered layer 121 that is not covered by the insulation layer 122 at the one main surface 10 of the element assembly 110. As a result, the Sn-containing layer 123 extends from each end surface of the element assembly 110 to the main surface 10 thereof.

Furthermore, the Sn-containing layer 123 covers a portion of the sintered layer 121 that is positioned on the one main surface 10 and is not covered by the insulation layer 122 at each side surface of the element assembly 110. Accordingly, the Sn-containing layer 123 extends from the one end surface of the element assembly 110 to the one main surface 10 of the element assembly 110 as well as to the side surfaces thereof. In addition, the Sn-containing layer 123 extends from the other end surface to the one main surface 10 of the element assembly 110 as well as to the side surfaces thereof.

The electronic component 100 having been manufactured in the manner described above is mounted by soldering. As the solder, Sn—Sb based solder, Sn—Cu based solder, or Sn—Ag based solder can be used.

FIG. 7 is a perspective view illustrating a state in which the electronic component according to the present preferred embodiment is mounted on a substrate by soldering. As shown in FIG. 7, the electronic component 100 is disposed on a substrate 20 so that cream solder which is patterned on the substrate 20 makes contact with the Sn-containing layer 123 of the outer electrode 120, and then the solder reflow is made, such that a solder fillet 30 is formed and the electronic component 100 is mounted on the substrate 20.

In the electronic component 100 according to the present preferred embodiment, because the insulation layer 122 is provided on the surface of the outer electrode 120, the solder fillet 30 cannot wet onto the insulation layer 122. Therefore, the fillet is provided only at a portion of the surface of the outer electrode 120 where the Sn-containing layer 123 that is not covered by the insulation layer 122 is positioned.

In other words, because the insulation layer 122 is arranged so as to extend across the entirety of each end surface of the element assembly 110 in the width direction W and across the entirety of each side surface of the element assembly 110 in the lengthwise direction L, wetting of the solder fillet 30 is reduced at the whole perimeter of the element assembly 110.

In the outer electrode 120 of the electronic component 100 according to the present preferred embodiment, as described above, because the insulation layer 122 is directly provided on the sintered layer 121, the insulation layer 122 is not separated when the cream solder and the Sn-containing layer 123 are melted and jointed together at the time of the reflow. This makes it possible to effectively reduce the wetting of the solder fillet 30.

Assuming that the insulation layer 122 is provided on the Sn-containing layer 123, when the reflow is carried out and the cream solder and the Sn-containing layer 123 are melted and jointed together, the insulation layer 122 that has been positioned on the melted Sn-containing layer 123 is separated. This allows the solder fillet to wet onto the Sn-containing layer 123 exposed to the exterior because of the separation of the insulation layer 122, thus making it difficult to effectively reduce the wetting of the solder fillet.

In the electronic component 100 according to the present preferred embodiment, the insulation layer 122 is provided at least at each end surface of the element assembly 110, thereby making it possible to reduce the wetting of the solder fillet 30 and prevent the generation of a crack in the element assembly 110 caused by tensile stress due to the thermal contraction of the solder fillet 30.

Furthermore, as described above, none of the inner electrodes 130 are located in the virtual plane P₁ that links the position of an edge of the insulation layer 122 at the end surface of the element assembly 110 on the one main surface 10 with the position of a tip of the outer electrode 120 on the one main surface 10 in the shortest distance. If a crack is generated by the tensile stress due to the thermal contraction of the solder fillet 30, the crack is likely to develop along the virtual surface P₁. Accordingly, because none of the inner electrodes 130 are located in the virtual plane P₁, cutting of the inner electrodes 130 due to the generation of a crack is significantly reduced or prevented. As a result, deterioration of electric characteristics of the electronic component 100 due to the generation of a crack is significantly reduced or prevented.

In addition, as described earlier, in the case where the dimension of distance between the one main surface 10 of the element assembly 110 and the edge portion on the one main surface 10 of the inner electrode 130 is taken as L₁, L₂ is the dimension of distance along the thickness direction T of the element assembly 110 between the one main surface 10 of the element assembly 110 and the position of an end portion on the one main surface 10 of the insulation layer 122 at each end surface of the element assembly 110, and the dimension of thickness of the element assembly 110 is taken as L_(T), the relation of L_(T)/10<L₂<L₁ is satisfied.

Satisfying the relation of L_(T)/10<L₂ makes it possible to form an adequate solder fillet 30 and ensure the orientation stability of the electronic component 100 at the time of mounting. Further, falling-off of the electronic component 100 having been mounted from the substrate 20 due to a shock or the like is significantly reduced or prevented.

It is preferable for the insulation layer 122 to cover the sintered layer 121 so as to be positioned to define the outermost layer at each side surface of the element assembly 110. With this, in the case where the plurality of electronic components 100 are mounted close to each other, even if the electronic components 100 are mounted in a state in which the side surfaces of the adjacent electronic components 100 make contact with each other because of insufficient stability in orientation of the electronic components 100 and the insulation layers 122 thereof are in contact with each other, it is possible to prevent the electronic components 100 that are in contact with each other from being electrically short-circuited.

By satisfying the relation of L₂<L₁, because the solder fillet 30 is not overlapping with a functional region as a region where the inner electrodes 130 are stacked within the element assembly 110, it can be made difficult for the tensile stress produced by the thermal contraction of the solder fillet 30 to act on the functional region. As a result, it is possible to significantly reduce or prevent the generation of a crack due to the thermal contraction of the solder fillet 30.

In addition, satisfying the relation of L₂<L₁ makes it possible to reduce generation of what is called “acoustic noise”. The reason for this is as follows.

In the case where the element assembly 110 is configured with a material having piezoelectricity or an electrostrictive property, if a DC voltage in which an AC voltage or an AC component is superposed is applied to the electronic component 100, mechanical distortion vibration is generated in the electronic component 100. Sound is generated from the substrate 20 when the distortion vibration is propagated to the substrate 20. Sound of no less than approximately 20 Hz and no more than approximately 20 kHz serves as an audible sound and gives displeasure to a person. The above phenomenon is what is called “acoustic noise”.

In the electronic component 100, it is the aforementioned functional region that becomes a generation source of the mechanical distortion vibration. The mechanical distortion vibration generated in the functional region is propagated from the outer electrode 120 to the substrate 20 through the solder fillet.

By satisfying the relation of L₂<L₁, because the solder fillet 30 is not overlapping with the functional region, it is possible to reduce the vibration that is propagated from the functional region to the substrate 20 through the solder fillet 30. As a result, the sound generated from the substrate 20 is reduced, in other words, the generation of the “acoustic noise” is reduced. In particular, this method, in which the above relation is satisfied, is noticeably effective for electronic components from which the “acoustic noise” is likely to be generated, such as a multilayer ceramic capacitor that includes the element assembly 110 including the dielectric layer 140 made of a dielectric material whose relative permittivity ∈_(r) is no less than approximately 3000, a multilayer ceramic capacitor whose nominal electrostatic capacity is no less than approximately 10 μF, and so on.

Hereinafter, an electronic component and a method for manufacturing the electronic component according to a second preferred embodiment of the present invention will be described. Note that because an electronic component 100 a according to the second preferred embodiment differs from the electronic component 100 according to the first preferred embodiment only in a point that the electronic component 100 a includes a reinforcement layer, description of the other constituent elements is not repeated herein.

Second Preferred Embodiment

FIG. 8 is a cross-sectional view illustrating a configuration of the electronic component according to the second preferred embodiment of the present invention. FIG. 9 is a flowchart illustrating a method for manufacturing the electronic component according to the second preferred embodiment of the present invention. Note that FIG. 8 illustrates a cross section of the electronic component viewed from the same direction as in FIG. 2.

As shown in FIG. 8, an outer electrode 120 a of the electronic component 100 a according to the second preferred embodiment of the present invention further includes a reinforcement layer 124 containing Ni or Cu. The reinforcement layer 124 is provided between the sintered layer 121 and the Sn-containing layer 123.

The reinforcement layer 124 is provided on the sintered layer 121 so as to cover the sintered layer 121 except for a portion of the sintered layer 121 that is covered by the insulation layer 122. In the present preferred embodiment, the reinforcement layer 124 extends from each end surface of the element assembly 110 to the one main surface 10 thereof. As described above, of the sintered layer 121 provided at each end surface of the element assembly 110, only a portion thereof on the one main surface 10 is not covered by the insulation layer 122. Accordingly, the reinforcement layer 124 covers the portion of the sintered layer 121 that is not covered by the insulation layer 122 and is positioned on the one main surface 10 at each end surface of the element assembly 110.

Further, the reinforcement layer 124 covers the sintered layer 121 that is not covered by the insulation layer 122 at the one main surface 10 of the element assembly 110. Furthermore, the reinforcement layer 124 covers a portion of the sintered layer 121 that is not covered by the insulation layer 122 and is positioned on the one main surface 10 at each side surface of the element assembly 110.

As described earlier, the sintered layer 121 extends from the one end surface of the element assembly 110 onto the main surfaces of the element assembly 110 and the side surfaces thereof. In addition, the sintered layer 121 extends from the other end surface of the element assembly 110 onto the main surfaces of the element assembly 110 and the side surfaces thereof.

As such, the reinforcement layer 124 extends from the one end surface of the element assembly 110 to the one main surface 10 of the element assembly 110 and to the side surfaces thereof. In addition, the reinforcement layer 124 extends from the other end surface of the element assembly 110 to the one main surface 10 of the element assembly 110 and to the side surfaces thereof.

As a material that configures the reinforcement layer 124, Ni, a Ni alloy, Cu, or a Cu alloy can be used. In the present preferred embodiment, the reinforcement layer 124 preferably is made of Ni, for example.

The reinforcement layer 124 may be arranged so as to overlie an end portion of the insulation layer 122 by several μm, for example. In this case, it is preferable for the insulation layer 122 to have a large surface roughness. Further, it is preferable for the dimension in length of the reinforcement layer 124 at a portion thereof that overlies the end portion of the insulation layer 122 along the thickness direction T of the element assembly 110 to be larger than the dimension in thickness of the reinforcement layer 124.

With this, the reinforcement layer 124 overlying the end portion of the insulation layer 122 penetrates into recessed areas in the surface of the insulation layer 122 in a spike-shaped configuration, thus enhancing the adhesiveness between the reinforcement layer 124 and the insulation layer 122. As a result, the boundary between the insulation layer 122 and the reinforcement layer 124 is so tightly bonded that the solder fillet entering the boundary between the insulation layer 122 and the reinforcement layer 124 is further reduced or prevented at the time of mounting.

In the present preferred embodiment, the Sn-containing layer 123 is provided on the reinforcement layer 124 so as to cover the sintered layer 121 except for a portion of the sintered layer 121 that is covered by the insulation layer 122, and defines another portion of the surface of the outer electrode 120 a.

As shown in FIG. 9, the method for manufacturing the electronic component 100 a according to the present preferred embodiment includes the process of preparing the element assembly 110 (S100), a process of providing the outer electrode 120 a on the surface of the element assembly 110 so as to be electrically connected with the inner electrodes 130 (S210).

The process of providing the outer electrode 120 a (S210) includes the process of providing the sintered layer 121 containing a sintered metal (S111), the process of providing the insulation layer 122 made of an electric insulation material (S112), a process of providing the reinforcement layer 124 containing Ni or Cu (S211), and the process of providing the Sn-containing layer 123 that contains Sn (S113).

In the process of providing the reinforcement layer 124 (S211), the reinforcement layer 124 is arranged so as to cover the sintered layer 121 except for a portion of the sintered layer 121 that is covered by the insulation layer 122. In the present preferred embodiment, the reinforcement layer 124 preferably is formed by electroplating. More specifically, the reinforcement layer 124 preferably is formed by barrel-plating. A barrel accommodating the plurality of element assemblies 110 provided with the sintered layer 121 and the insulation layer 122 is immersed in a plating liquid within a plating bath, and is electrified while the barrel being rotated in the plating liquid, such that the reinforcement layer 124 is provided on the sintered layer 121 except for the portion of the sintered layer 121 that is covered by the insulation layer 122.

As described above, of the sintered layer 121 provided at each end surface of the element assembly 110, only a portion thereof that is provided on the one main surface 10 is not covered by the insulation layer 122. Accordingly, the reinforcement layer 124 covers the portion of the sintered layer 121 that is positioned on the one main surface 10 and is not covered by the insulation layer 122 at each end surface of the element assembly 110. Further, the reinforcement layer 124 is configured to cover the sintered layer 121 that is not covered by the insulation layer 122 at the one main surface 10 of the element assembly 110. As a result, the reinforcement layer 124 extends from each end surface of the element assembly 110 to the main surface 10 thereof.

Furthermore, the reinforcement layer 124 covers a portion of the sintered layer 121 that is positioned on the one main surface 10 and is not covered by the insulation layer 122 at each side surface of the element assembly 110. Accordingly, the reinforcement layer 124 extends from the one end surface of the element assembly 110 to the one main surface 10 of the element assembly 110 as well as to the side surfaces thereof. In addition, the reinforcement layer 124 extends from the other end surface of the element assembly 110 to the one main surface 10 of the element assembly 110 as well as to the side surfaces thereof.

In the process of providing the Sn-containing layer 123 (S113), the Sn-containing layer 123 is provided on the reinforcement layer 124 so as to cover the sintered layer 121 except for a portion of the sintered layer 121 that is covered by the insulation layer 122 to constitute another portion of the surface of the outer electrode 120.

In the present preferred embodiment, the Sn-containing layer 123 preferably is formed by electroplating. More specifically, the Sn-containing layer 123 preferably is formed by barrel-plating. That is, a barrel accommodating the plurality of element assemblies 110 provided with the sintered layer 121, the insulation layer 122, and the reinforcement layer 124 is immersed in a plating liquid within a plating bath, and is electrified while the barrel being rotated in the plating liquid, such that the Sn-containing layer 123 is provided on the reinforcement layer 124. As a result, the Sn-containing layer 123 extends from each end surface of the element assembly 110 to the one main surface 10 thereof. In addition, the Sn-containing layer 123 is provided on the reinforcement layer 124 at each surface of the element assembly 110.

Accordingly, the Sn-containing layer 123 extends from the one end surface of the element assembly 110 to the one main surface 10 of the element assembly 110 as well as to each side surface thereof. In addition, the Sn-containing layer 123 extends from the other end surface of the element assembly 110 to the one main surface 10 of the element assembly 110 as well as to each side surface thereof.

Also in the electronic component 100 a according to the present preferred embodiment, the insulation layer 122 is provided at least at each end surface of the element assembly 110, thus making it possible to reduce the wetting of the solder fillet 30 and prevent the generation of a crack in the element assembly 110 caused by tensile stress due to the thermal contraction of the solder fillet 30.

Hereinafter, an electronic component and a method for manufacturing the electronic component according to a third preferred embodiment of the present invention will be described. Note that because an electronic component 100 b according to the third preferred embodiment differs from the electronic component 100 a according to the second preferred embodiment only in a point that the electronic component 100 b includes a base layer, description of the other constituent elements is not repeated herein.

Third Preferred Embodiment

FIG. 10 is a cross-sectional view illustrating a configuration of the electronic component according to the third preferred embodiment of the present invention. FIG. 11 is a flowchart illustrating a method for manufacturing the electronic component according to the third preferred embodiment of the present invention. Note that FIG. 10 illustrates a cross section of the electronic component viewed from the same direction as in FIG. 2.

As shown in FIG. 10, an outer electrode 120 b of the electronic component 100 b according to the third preferred embodiment of the present invention further includes a base layer 125 configured of a material different from that of the reinforcement layer 124 and containing Cu or Ni. The base layer 125 is provided between the sintered layer 121 and the reinforcement layer 124.

The base layer 125 is provided on the sintered layer 121 so as to cover the sintered layer 121 except for a portion of the sintered layer 121 that is covered by the insulation layer 122. In the present preferred embodiment, the base layer 125 extends from each end surface of the element assembly 110 to the one main surface 10 thereof. As described above, of the sintered layer 121 provided at each end surface of the element assembly 110, only a portion thereof on the one main surface 10 is not covered by the insulation layer 122. Accordingly, the base layer 125 covers the portion of the sintered layer 121 that is not covered by the insulation layer 122 and is positioned on the one main surface 10 at each end surface of the element assembly 110.

Further, the base layer 125 covers the sintered layer 121 that is not covered by the insulation layer 122 at the one main surface 10 of the element assembly 110. Furthermore, the base layer 125 covers a portion of the sintered layer 121 that is not covered by the insulation layer 122 and is positioned on the one main surface 10 at each side surface of the element assembly 110.

As described earlier, the sintered layer 121 extends from the one end surface of the element assembly 110 onto the main surfaces of the element assembly 110 and the side surfaces thereof. In addition, the sintered layer 121 extends from the other end surface of the element assembly 110 onto the main surfaces of the element assembly 110 and the side surfaces thereof.

As such, the base layer 125 extends from the one end surface of the element assembly 110 to the one main surface 10 of the element assembly 110 and to the side surfaces thereof. In addition, the base layer 125 extends from the other end surface of the element assembly 110 to the one main surface 10 of the element assembly 110 and to the side surfaces thereof.

As a material that configures the base layer 125, a material that differs from the material configuring the reinforcement layer 124 such as Ni, a Ni alloy, Cu, or a Cu alloy can be used. In the present preferred embodiment, the base layer 125 preferably is made of Cu, for example.

The base layer 125 may be arranged so as to overlie an end portion of the insulation layer 122 by several μm, for example. In this case, it is preferable for the insulation layer 122 to have a large surface roughness. Further, it is preferable for the dimension in length of the base layer 125 at a portion thereof that overlies the end portion of the insulation layer 122 along the thickness direction T of the element assembly 110 to be larger than the dimension in thickness of the base layer 125.

With this, the base layer 125 overlying the end portion of the insulation layer 122 penetrates into recessed areas in the surface of the insulation layer 122 in a spike-shaped form, thus enhancing the adhesiveness between the base layer 125 and the insulation layer 122. As a result, the boundary between the insulation layer 122 and the base layer 125 is so tightly bonded that the solder fillet entering the boundary between the insulation layer 122 and the base layer 125 is further reduced at the time of mounting.

In the present preferred embodiment, the reinforcement layer 124 is provided on the base layer 125 so as to cover the entirety of the base layer 125. In the present preferred embodiment, the reinforcement layer 124 preferably is made of Ni, for example.

As shown in FIG. 11, the method for manufacturing the electronic component 100 b according to the present preferred embodiment includes the process of preparing the element assembly 110 (S100), and a process of providing the outer electrode 120 b on the surface of the element assembly 110 so as to be electrically connected with the inner electrodes 130 (S310).

The process of providing the outer electrode 120 b (S310) includes the process of providing the sintered layer 121 containing a sintered metal (S111), the process of providing the insulation layer 122 made of an electric insulation material (S112), a process of providing the base layer 125 configured of a material different from that of the reinforcement layer 124 and containing Cu or Ni (S311), the process of providing the reinforcement layer 124 containing Ni or Cu (S211), and the process of providing the Sn-containing layer 123 that contains Sn (S113).

In the process of providing the base layer 125 (S311), the base layer 125 is provided between the sintered layer 121 and the reinforcement layer 124.

In the present preferred embodiment, the base layer 125 preferably is formed by electroplating. More specifically, the base layer 125 preferably is formed by barrel-plating. That is, a barrel accommodating the plurality of element assemblies 110 provided with the sintered layer 121 and the insulation layer 122 is immersed in a plating liquid within a plating bath, and is electrified while the barrel being rotated in the plating liquid, such that the base layer 125 is provided on the sintered layer 121 except for a portion of the sintered layer 121 that is covered by the insulation layer 122.

As described above, of the sintered layer 121 provided at each end surface of the element assembly 110, only a portion thereof that is on the one main surface 10 is not covered by the insulation layer 122. Accordingly, the base layer 125 covers the portion of the sintered layer 121 that is positioned on the one main surface 10 and is not covered by the insulation layer 122 at each end surface of the element assembly 110. Further, the base layer 125 is configured to cover the sintered layer 121 that is not covered by the insulation layer 122 at the one main surface 10 of the element assembly 110. As a result, the base layer 125 extends from each end surface of the element assembly 110 to the main surface 10 thereof.

Furthermore, the base layer 125 covers a portion of the sintered layer 121 that is positioned on the one main surface 10 and is not covered by the insulation layer 122 at each of the side surfaces of the element assembly 110. Accordingly, the base layer 125 extends from the one end surface of the element assembly 110 to the one main surface 10 of the element assembly 110 as well as to each of the side surfaces thereof. In addition, the base layer 125 extends from the other end surface of the element assembly 110 to the one main surface 10 of the element assembly 110 as well as to each of the side surfaces thereof.

In the present preferred embodiment, the reinforcement layer 124 preferably is formed by electroplating. More specifically, the reinforcement layer 124 preferably is formed by barrel-plating. That is, the barrel accommodating the plurality of element assemblies 110 provided with the sintered layer 121, the insulation layer 122, and the base layer 125 is immersed in a plating liquid within the plating bath, and is electrified while the barrel being rotated in the plating liquid, such that the reinforcement layer 124 is provided on the base layer 125.

By providing the reinforcement layer 124 on the base layer 125, the reinforcement layer 124 can be formed by plating more easily in comparison with a case in which the reinforcement layer 124 is provided on the sintered layer 121.

Also in the electronic component 100 b according to the present preferred embodiment, the insulation layer 122 is provided at least at each end surface of the element assembly 110, thus making it possible to reduce the wetting of the solder fillet 30 and prevent the generation of a crack in the element assembly 110 caused by tensile stress due to the thermal contraction of the solder fillet 30.

Hereinafter, an electronic component according to a fourth preferred embodiment of the present invention will be described. Note that because an electronic component 400 according to the fourth preferred embodiment differs from the electronic component 100 according to the first preferred embodiment only in a point that the positions of the insulation layer and Sn-containing layer are different from those in the first preferred embodiment, description of the other constituent elements is not repeated herein.

Fourth Preferred Embodiment

FIG. 12 is a perspective view illustrating an external appearance of the electronic component according to the fourth preferred embodiment of the present invention. FIG. 13 is a cross-sectional view of the electronic component taken along a XIII-XIII arrow line in FIG. 12.

As shown in FIGS. 12 and 13, the electronic component 400 according to the fourth preferred embodiment of the present invention includes the element assembly 110 and outer electrodes 420 provided on the surface of the element assembly 110 and electrically connected with the inner electrodes 130. The outer electrodes 420 each include the sintered layer 121 containing a sintered metal, an insulation layer 422 formed of an electric insulation material, and a Sn-containing layer 423 that contains Sn.

The insulation layer 422 is directly provided on the sintered layer 121 at each end surface so as to extend in the width direction W, which is a direction perpendicular or substantially perpendicular to the side surface of the element assembly 110, and constitutes a portion of a surface of the outer electrode 420.

In the present preferred embodiment, the insulation layer 422 extends across the entirety in the width direction W of the element assembly 110 at each end surface of the element assembly 110. As shown in FIG. 13, none of the inner electrodes 130 are located in the virtual plane P₁ that links the position of an edge of the insulation layer 422 at the end surface of the element assembly 110 on the one main surface 10 thereof with the position of a tip of the outer electrode 420 on the one main surface 10 of the element assembly 110 in the shortest distance.

Note that in the present preferred embodiment, as shown in FIG. 13, although none of the inner electrodes 130 intersect with the virtual lines defining the virtual plane P₁ in a cross section of the electronic component 400 on an arbitrary surface in parallel to the side surface of the element assembly 110, the inner electrodes 130 intersecting with the virtual lines may be included therein. However, it is preferable that none of the inner electrodes 130 intersect with the virtual lines.

The insulation layer 422 is directly provided on the sintered layer 121 at each end surface of the element assembly 110 so that at least a portion of the insulation layer 422 is located between the one main surface 10 of the element assembly 110 and the position of an edge portion of the inner electrode 130 closest to the one main surface 10 of the element assembly 110 in the thickness direction T, which is a direction perpendicular or substantially perpendicular to the main surface of the element assembly 110.

To be more specific, in the case where the dimension of distance between the one main surface 10 of the element assembly 110 and the edge portion on the one main surface 10 of the inner electrode 130 is taken as L₁, the dimension of distance L₂ along the thickness direction T of the element assembly 110 between the one main surface 10 of the element assembly 110 and the position of an end portion on the one main surface 10 of the insulation layer 422 satisfies the relation of L₂<L₁, at each end surface of the element assembly 110.

In the present preferred embodiment, L₂>0; that is, of the sintered layer 121 provided at each of the end surfaces of the element assembly 110, a portion of the sintered layer 121 on the one main surface 10 is not covered by the insulation layer 422. In the case where the dimension of thickness of the element assembly 110 is taken as L_(T), it is more preferable for the relation of L₂>L_(T)/10 to be satisfied. Accordingly, in the electronic component 400, it is preferable for both the relation of L₂<L₁ and the relation of L₂>L_(T)/10 to be satisfied. The electronic component 400 satisfies the relation of L_(T)/10<L₂<L₁ in the present preferred embodiment.

As shown in FIG. 13, the insulation layer 422 is arranged such that none of the inner electrodes 130 are located in a virtual plane P₂ that links the position of an edge of the insulation layer 422 at the end surface of the element assembly 110 on the other main surface 11 with the position of a tip of the outer electrode 420 on the other main surface 11 of the element assembly 110 in the shortest distance.

Note that in the present preferred embodiment, as shown in FIG. 13, although none of the inner electrodes 130 intersect with virtual lines defining the virtual plane P₂ in a cross section of the electronic component 400 on an arbitrary surface in parallel to the side surface of the element assembly 110, the inner electrodes 130 intersecting with the virtual lines may be included therein. However, it is preferable that none of the inner electrodes 130 intersect with the virtual lines.

The insulation layer 422 is directly provided on the sintered layer 121 at each end surface of the element assembly 110 such that at least a portion of the insulation layer 422 is located between the other main surface 11 of the element assembly 110 and the position of an edge portion of the inner electrode 130 closest to the other main surface 11 of the element assembly 110 in the thickness direction T, which is a direction perpendicular or substantially perpendicular to the main surface of the element assembly 110.

To be more specific, in the case where a dimension of distance between the other main surface 11 of the element assembly 110 and an edge portion on the other main surface 11 of the inner electrode 130 closest to the other main surface 11 is taken as L₃, a dimension of distance L₄ along the thickness direction T of the element assembly 110 between the other main surface 11 of the element assembly 110 and the position of an end portion on the other main surface 11 of the insulation layer 422 satisfies a relation of L₄<L₃, at each end surface of the element assembly 110.

In the present preferred embodiment, L₄>0; that is, of the sintered layer 121 provided at each of the end surfaces of the element assembly 110, a portion of the sintered layer 121 on the other main surface 11 is not covered by the insulation layer 422. In the case where the dimension of thickness of the element assembly 110 is taken as L_(T), it is more preferable for a relation of L₄>L_(T)/10 to be satisfied. Accordingly, in the electronic component 400, it is preferable for both the relation of L₄<L₃ and the relation of L₄>L_(T)/10 to be satisfied. The electronic component 400 satisfies a relation of L_(T)/10<L₄<L₃ in the present preferred embodiment.

The insulation layer 422 extends in the lengthwise direction L, which is a direction perpendicular or substantially perpendicular to the end surface of the element assembly 110, at each side surface of the element assembly 110. In the present preferred embodiment, the insulation layer 422 extends across the entirety of each side surface of the element assembly 110 along the lengthwise direction L of the element assembly 110. In other words, a portion of the insulation layer 422 is directly provided on the sintered layer 121 at each side surface of the element assembly 110. Another portion of the insulation layer 422 is directly provided on each side surface of the element assembly 110.

The insulation layer 422 provided at each end surface of the element assembly 110 and the insulation layer 422 provided at each side surface of the element assembly 110 are connected with each other so as to define a ring shape. At each side surface of the element assembly 110, L₂ is the dimension of distance along the thickness direction T of the element assembly 110 between the one main surface 10 of the element assembly 110 and the position of the end portion on the one main surface 10 of the insulation layer 422. At each side surface of the element assembly 110, L₄ is the dimension of distance along the thickness direction T of the element assembly 110 between the other main surface 11 of the element assembly 110 and the position of the end portion on the other main surface 11 of the insulation layer 422. In the present preferred embodiment, the dimension L₂ and the dimension L₄ are the same.

As a method for forming the insulation layer 422, the following may be used, for example. That is, in a state in which the plurality of element assemblies 110 provided with the sintered layer 121 are arranged with a space therebetween and sandwiched between two elastic plates, a softened insulating resin is poured between the two plates, thus applying the insulating resin on the surface of the element assemblies 110 provided with the sintered layer 121. Through this, because the insulating resin does not adhere to the element assembly 110 provided with the sintered layer 121 at portions that are sunk in the two plates, the insulation layer 422 is provided.

The Sn-containing layer 423 is arranged on the sintered layer 121 so as to cover the sintered layer 121 except for a portion of the sintered layer 121 that is covered by the insulation layer 422, and constitutes another portion of the surface of the outer electrode 420.

In the present preferred embodiment, the Sn-containing layer 423 extends from each end surface of the element assembly 110 to the one main surface 10 of the element assembly 110 as well as to the other main surface 11 thereof. As described before, of the sintered layer 121 provided at each end surface of the element assembly 110, a portion of the sintered layer 121 on the one main surface 10 and a portion of the sintered layer 121 on the other main surface 11 are not covered by the insulation layer 422. Accordingly, at each end surface of the element assembly 110, the Sn-containing layer 423 covers the portion of the sintered layer 121 positioned on the one main surface 10 and the portion of the sintered layer 121 positioned on the other main surface 11.

Further, the Sn-containing layer 423 covers the sintered layer 121 that is not covered by the insulation layer 422 at the one main surface 10 of the element assembly 110 and the other main surface 11 thereof. Furthermore, at each side surface of the element assembly 110, the Sn-containing layer 423 covers a portion of the sintered layer 121 that is positioned on the one main surface 10 and is not covered by the insulation layer 422 and a portion of the sintered layer 121 that is positioned on the other main surface 11 and is not covered by the insulation layer 422.

As described earlier, the sintered layer 121 extends from the one end surface of the element assembly 110 onto both the main surfaces and the side surfaces of the element assembly 110. Further, the sintered layer 121 extends from the other end surface of the element assembly 110 onto both the main surfaces and the side surfaces of the element assembly 110.

As such, the Sn-containing layer 423 extends from the one end surface of the element assembly 110 to the one main surface 10 and to the side surfaces of the element assembly 110. Likewise, the Sn-containing layer 423 extends from the one end surface of the element assembly 110 to the other main surface 11 and to the side surfaces of the element assembly 110.

Furthermore, the Sn-containing layer 423 extends from the other end surface of the element assembly 110 to the one main surface 10 and to the side surfaces of the element assembly 110. Likewise, the Sn-containing layer 423 extends from the other end surface of the element assembly 110 to the other main surface 11 and to the side surfaces of the element assembly 110.

In the present preferred embodiment, in the outer electrode 420 of the electronic component 400, either of the one main surface 10 and the other main surface 11 of the element assembly 110 can be selected as a mounting surface with respect to the substrate 20.

In other words, in the outer electrode 420 of the electronic component 400, regardless of which one of the one main surface 10 and the other main surface 11 of the element assembly 110 is selected as the mounting surface, it is possible to reduce the wetting of the solder fillet 30 and prevent the generation of a crack in the element assembly 110 caused by tensile stress due to the thermal contraction of the solder fillet 30.

Therefore, in the electronic component 400 according to the present preferred embodiment, the electronic component 400 is capable of being mounted without being limited by the orientation of the electronic component 400 in the thickness direction T of the element assembly 110.

Hereinafter, an electronic component according to a fifth preferred embodiment of the present invention will be described. Because an electronic component 500 according to the fifth preferred embodiment differs from the electronic component 100 according to the first preferred embodiment only in a point that the stacking direction of the inner electrodes is different from that in the first preferred embodiment, description of the other constituent elements is not repeated herein.

Fifth Preferred Embodiment

FIG. 14 is a perspective view illustrating an external appearance of the electronic component according to the fifth preferred embodiment of the present invention. FIG. 15 is a cross-sectional view of the electronic component taken along a XV-XV arrow line in FIG. 14. FIG. 16 is a cross-sectional view of the electronic component taken along a XVI-XVI arrow line in FIG. 14. FIG. 17 is a cross-sectional view of the electronic component taken along a XVII-XVII arrow line in FIG. 15 and of the electronic component taken along the XVII-XVII arrow line in FIG. 16 as well. FIG. 18 is a cross-sectional view of the electronic component taken along a XVIII-XVIII arrow line in FIG. 15 and of the electronic component taken along the XVIII-XVIII arrow line in FIG. 16 as well. In FIG. 14, a lengthwise direction of an element assembly is indicated by “L”, a width direction of the element assembly is indicated by “W”, and a thickness direction of the element assembly is indicated by “T”.

As shown in FIGS. 14 through 18, the electronic component 500 according to the fifth preferred embodiment of the present invention includes a parallelepiped element assembly 510 in which the inner electrodes 130 are embedded, and the outer electrode 120 provided on a surface of the element assembly 510 and electrically connected with the inner electrodes 130.

In the element assembly 510, the dielectric layers 140 and the inner electrodes 130 having a plate shape are alternately stacked. The stacking direction of the dielectric layers 140 and the inner electrodes 130 is perpendicular or substantially perpendicular to both the lengthwise direction L of the element assembly 510 and the thickness direction T of the element assembly 510. In other words, the stacking direction of the dielectric layers 140 and the inner electrodes 130 is parallel to the width direction W of the element assembly 510.

The element assembly 510 includes a pair of main surfaces perpendicular or substantially perpendicular to the thickness direction T, a pair of end surfaces perpendicular or substantially perpendicular to the lengthwise direction L, and a pair of side surfaces perpendicular or substantially perpendicular to the width direction W. The pair of main surfaces includes the one main surface 10 and the other main surface 11. The one main surface 10 is a surface positioned on a mounting surface of the electronic component 500 when the electronic component 500 is mounted. In other words, when the electronic component 500 is mounted on a substrate, the one main surface 10 is a surface that opposes the substrate.

As described above, the element assembly 510 includes the pair of side surfaces perpendicular or substantially perpendicular to the stacking direction of the dielectric layers 140 and the inner electrodes 130, the pair of main surfaces respectively connecting the side surfaces, and the pair of end surfaces respectively perpendicular or substantially perpendicular to the pair of main surfaces and the pair of side surfaces.

Although the element assembly 510 is formed in a parallelepiped-like shape with its corners being rounded, the corners of the assembly may not be rounded. Furthermore, concave and/or convex portions may be formed in any one of the surfaces included in the pair of main surfaces, the pair of end surfaces, or the pair of side surfaces.

In the inner electrodes 130 adjacent to each other and opposing each other, one inner electrode 130 is electrically connected with the outer electrode 120 at one end surface of the element assembly 510, while the other inner electrode 130 is electrically connected with the outer electrode 120 at the other end surface of the element assembly 510.

In the present preferred embodiment, the insulation layer 122 extends across the entirety in the width direction of the element assembly 510 at each end surface of the element assembly 510. As shown in FIGS. 15 and 16, none of the inner electrodes 130 are located in a virtual plane P₁ that links the position of an edge of the insulation layer 122 at the end surface of the element assembly 510 on the one main surface 10 with the position of a tip of the outer electrode 120 on the one main surface 10 of the element 510 in the shortest distance.

Note that in the present preferred embodiment, as shown in FIGS. 15 and 16, although none of the inner electrodes 130 intersect with virtual lines defining the virtual plane P₁ in a cross section of the electronic component 500 on an arbitrary surface parallel or substantially parallel to the side surface of the element assembly 510, the inner electrodes 130 intersecting with the virtual lines may be included therein. However, it is preferable that none of the inner electrodes 130 intersect with the virtual lines.

The insulation layer 122 is directly provided on the sintered layer 121 at each end surface of the element assembly 510 so that at least a portion of the insulation layer 122 is located between the one main surface 10 of the element assembly 510 and the position of an edge portion of the inner electrode 130 closest to the one main surface 10 of the element assembly 510 in the thickness direction T, which is a direction perpendicular or substantially perpendicular to the main surface of the element assembly 510.

To be more specific, in the case where a dimension of distance between the one main surface 10 of the element assembly 510 and an edge on the one main surface 10 of the inner electrode 130 is taken as L₅, the dimension of distance L₂ along the thickness direction T of the element assembly 510 between the one main surface 10 of the element assembly 510 and the position of an end portion on the one main surface 10 of the insulation layer 122 satisfies a relation of L₂<L₅, at each end surface of the element assembly 510.

In the present preferred embodiment, L₂>0; that is, of the sintered layer 121 provided at each of the end surfaces of the element assembly 510, only a portion of the sintered layer 121 on the one main surface 10 is not covered by the insulation layer 122. In the case where the dimension of thickness of the element assembly 510 is taken as L_(T), it is preferable for the relation of L₂>L_(T)/10 to be satisfied. Accordingly, in the electronic component 500, it is preferable for both the relation of L₂<L₅ and the relation of L₂>L_(T)/10 to be satisfied. The electronic component 500 satisfies a relation of L_(T)/10<L₂<L₅ in the present preferred embodiment.

Further, the insulation layer 122 extends in the lengthwise direction L, which is a direction perpendicular or substantially perpendicular to the end surface of the element assembly 510, at each of the side surfaces of the element assembly 510. In the present preferred embodiment, the insulation layer 122 extends across the entirety of each side surface of the element assembly 510 along the lengthwise direction L of the element assembly 510. In other words, a portion of the insulation layer 122 is directly provided on the sintered layer 121 at each side surface of the element assembly 510. Another portion of the insulation layer 122 is directly provided on each side surface of the element assembly 510.

The insulation layer 122 provided at each end surface of the element assembly 510 and the insulation layer 122 provided at each side surface of the element assembly 510 are connected with each other so as to define a ring-shaped configuration. At each side surface of the element assembly 510, L₂ is the dimension of distance along the thickness direction T of the element assembly 510 between the one main surface 10 of the element assembly 510 and the position of the end portion on the one main surface 10 of the insulation layer 122.

Further, the insulation layer 122 covers the entirety of the other main surface 11 of the element assembly 510. In other words, a portion of the insulation layer 122 is directly provided on the sintered layer 121 at the other main surface 11 of the element assembly 510. Another portion of the insulation layer 122 is directly provided on the other main surface 11 of the element assembly 510. The insulation layer 122 covering the other main surface 11 of the element assembly 510 is connected with the insulation layer 122 provided at each end surface of the element assembly 510 and the insulation layer 122 provided at each side surface of the element assembly 510, respectively.

As described above, portions of the insulation layer 122 are directly provided on the other main surface 11 of the element assembly 510 and the side surfaces of the element assembly 510. The insulation layer 122 has a higher adhesiveness with the element assembly 510 than that with the sintered layer 121. Therefore, providing a portion of the insulation layer 122 directly on the element assembly 510 makes it possible to prevent the separation of the insulation layer 122 at the time of plating or mounting.

In the present preferred embodiment, the Sn-containing layer 123 extends from each end surface of the element assembly 510 to the one main surface 10. As described above, of the sintered layer 121 provided at each end surface of the element assembly 510, only a portion of the sintered layer 121 on the one main surface 10 is not covered by the insulation layer 122. Accordingly, at each end surface of the element assembly 510, the Sn-containing layer 123 covers the portion of the sintered layer 121 that is positioned on the one main surface 10 and is not covered by the insulation layer 122.

In addition, the Sn-containing layer 123 covers the sintered layer 121 that is not covered by the insulation layer 122 at the one main surface 10 of the element assembly 510. Furthermore, at each side surface of the element assembly 510, the Sn-containing layer 123 covers a portion of the sintered layer 121 that is positioned on the one main surface 10 and is not covered by the insulation layer 122.

As described above, the sintered layer 121 extends from the one end surface of the element assembly 510 onto both the main surfaces and the side surfaces thereof. Further, the sintered layer 121 extends from the other end surface of the element assembly 510 onto both the main surfaces and the side surfaces thereof.

As such, the Sn-containing layer 123 extends from the one end surface of the element assembly 510 to the one main surface 10 and to the side surfaces thereof. Further, the Sn-containing layer 123 extends from the other end surface of the element assembly 510 to the one main surface 10 and to the side surfaces thereof.

The Sn-containing layer 123 extending from the one end surface of the element assembly 510 to the one main surface 10 as well as to the side surfaces of the element assembly 510 and the Sn-containing layer 123 extending from the other end surface of the element assembly 510 to the one main surface 10 as well as to the side surfaces of the element assembly 510, are separated from each other and not electrically connected.

Also in the electronic component 500 according to the present preferred embodiment, the insulation layer 122 is provided at least at each end surface of the element assembly 510, thus making it possible to reduce the wetting of the solder fillet 30 and significantly reduce or prevent the generation of a crack in the element assembly 510 caused by tensile stress due to the thermal contraction of the solder fillet 30.

As described above, none of the inner electrodes 130 are located in the virtual plane P₁ that links the position of an edge of the insulation layer 122 at the end surface of the element assembly 510 on the one main surface 10 with the position of a tip of the outer electrode 120 on the one main surface 10 in the shortest distance. If a crack is generated by the tensile stress due to the thermal contraction of the solder fillet, the crack is likely to develop along the virtual surface P₁. Accordingly, because none of the inner electrodes 130 are located in the virtual plane P₁, cutting of the inner electrodes 130 due to the generation of a crack is significantly reduced or prevented. As a result, deterioration of electric characteristics of the electronic component 500 due to the generation of a crack is significantly reduced or prevented.

In addition, as described earlier, in the case where the dimension of distance between the one main surface 10 of the element assembly 510 and the edge portion on the one main surface of the inner electrode 130 is L₅, L₂ is the dimension of distance along the thickness direction T of the element assembly 510 between the one main surface 10 of the element assembly 510 and the position of an end portion on the one main surface 10 of the insulation layer 122 at each end surface of the element assembly 510, and the dimension of thickness of the element assembly 510 is L_(T), the relation of L_(T)/10<L₂<L₅ is satisfied.

Satisfying the relation of L_(T)/10<L₂ makes it possible to form an adequate solder fillet and ensure orientation stability of the electronic component 500 at the time of mounting. Further, falling-off of the electronic component 500 having been mounted from the substrate due to a shock or the like is significantly reduced or prevented.

It is preferable for the insulation layer 122 to cover the sintered layer 121 so as to be positioned as the outermost layer at each side surface of the element assembly 510. With this, in the case where the plurality of electronic components 500 are mounted close to each other, even if the electronic components 500 are mounted in a state in which the side surfaces of the adjacent electronic components 500 make contact with each other because of insufficient stability in orientation of the electronic components 500 and consequently the insulation layers 122 thereof are in contact with each other, it is possible to prevent the electronic components 500 that are in contact with each other from being electrically short-circuited.

By satisfying the relation of L₂<L₅, because the solder fillet is not overlapping with a functional region as a region where the inner electrodes 130 are stacked within the element assembly 510, the tensile stress produced by thermal contraction of the solder fillet can be made difficult to act on the functional region. As a result, it is possible to significantly reduce or prevent the generation of a crack due to the thermal contraction of the solder fillet.

The stacking directions of the inner electrodes 130 in the electronic component 100 a according to the second preferred embodiment, the electronic component 100 b according to the third preferred embodiment, and the electronic component 400 according to the fourth preferred embodiment may respectively be set to be the same as the stacking direction of the electronic components 500 in the present preferred embodiment.

It should be noted that the preferred embodiments disclosed in the present specification are merely examples and are not limiting in any way. The scope of the present invention is not indicated by the description made above, but by the appended claims, and further, meanings equivalent to the appended claims and any modification that is made within the range of the appended claims are intended to be included in the scope of the present invention.

While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims. 

What is claimed is:
 1. An electronic component comprising: an element assembly in which inner electrodes are embedded and including a pair of main surfaces, a pair of side surfaces respectively connecting the main surfaces, and a pair of end surfaces respectively perpendicular or substantially perpendicular to the pair of main surfaces and the pair of side surfaces; and an outer electrode provided on a surface of the element assembly and electrically connected with the inner electrodes; wherein the outer electrode includes a sintered layer including a sintered metal, an insulation layer including an electric insulation material, and a Sn-containing layer including Sn; the sintered layer extends from each of the end surfaces onto at least one of the main surfaces so as to cover each of the end surfaces; the insulation layer is directly provided on the sintered layer at each of the end surfaces so as to extend in a direction perpendicular or substantially perpendicular to the side surfaces and constitutes a portion of a surface of the outer electrode; and the Sn-containing layer covers the sintered layer except for a portion of the sintered layer that is covered by the insulation layer and constitutes another portion of the surface of the outer electrode.
 2. The electronic component according to claim 1, wherein the Sn-containing layer extends from each of the end surfaces to one of the main surfaces.
 3. The electronic component according to claim 2, wherein none of the inner electrodes are located in a virtual plane that links a position of an edge of the insulation layer at the end surface on one of the main surfaces with a position of a tip of the outer electrode on one of the main surfaces in a shortest distance.
 4. The electronic component according to claim 2, wherein the insulation layer is directly provided on the sintered layer at each of the end surfaces so that at least a portion of the insulation layer is located between one of the main surfaces and a position of an edge portion of the inner electrode closest to one of the main surfaces in a direction perpendicular or substantially perpendicular to the main surface.
 5. The electronic component according to claim 1, wherein the sintered layer extends from each of the end surfaces onto each of the side surfaces; and the insulation layer is provided directly on the sintered layer at each of the side surfaces so as to extend in a direction perpendicular or substantially perpendicular to the end surface.
 6. The electronic component according to claim 1, wherein the outer electrode further includes a reinforcement layer containing Ni or Cu; and the reinforcement layer is provided between the sintered layer and the Sn-containing layer.
 7. The electronic component according to claim 6, wherein the outer electrode further includes a base layer which is made of a material different from a material of the reinforcement layer and contains Cu or Ni; and the base layer is provided between the sintered layer and the reinforcement layer.
 8. The electronic component according to claim 1, wherein the electronic component is one of a ceramic capacitor, a piezoelectric component, a thermistor, and an inductor. 